1. Field of the Invention
The present invention is directed to novel compositions, materials, methods of their use and methods of their manufacture that are generally useful as agents in the construction and building trades. More specifically, the methods and compositions of the present invention can be used in construction and building applications that benefit from concrete compositions having structural strength properties and less than normal weight.
2. Description of the Prior Art
Expanded polymers have been incorporated into concrete formulations for the purpose of lowering the density or weight of the final cured and hardened concrete. Past practice has been to replace the fine aggregate or sand portion of a concrete mix with expanded polymers; however, this approach, while providing concrete with a lower weight or density, does not provide concrete with the physical properties required for structural applications.
U.S. Pat. Nos. 3,214,393; 3,257,338; 3,272,765; 4,040,855; 4,265,964; 5,472,498; 5,580,378; 5,622,556; 5,725,652; and 6,875,266 are non-limiting examples where the density of concrete has been reduced by replacing coarse aggregate with expandable polystyrene (EPS).
Accepted practice in the concrete industry to improve concrete strength in various mix designs is to reduce the water content in the mix. However, a decrease in the proportion of coarse aggregate to fine aggregate increases the water demand in a concrete mix. When strength is to be maximized, the amount of coarse aggregate is maintained at high levels (see generally, Kosmatka et al., Design and Control of Concrete Mixtures, Fourteenth Edition, Portland Cement Association, 2002, pages 2 and 155).
There remains a need in the art to provide light weight concrete formulations using expanded polymers that also possess the physical properties to be used in structural applications.